2.12
The market's inability to achieve equity
Why a free market, working as intended, leaves income and wealth unequally distributed, shown with the circular flow of income.
Level and scope checked against the Economics guide (course first assessed 2022; October 2022 update), pp. 20–21, 33, on 10 Nov 2026. AI-assisted check, not reviewed by a teacher.
Contents
- 1Learning objectives and review statusHL
- 2How a free market distributes incomeHL
- 3Why the result is unequal, and why it persistsHL
- 4Efficient is not the same as equitableHL
- 5Practice and feedback: 10 marksHL
- 6Practice and feedback: 2 marksHL
- 7Practice and feedback: 4 marksHL
- 8Practice and feedback: 4 marksHL
- 9Sources and review statusHL
1Learning objectives and review statusHL only
- Use a circular flow diagram to show where household income comes from in a free market.
- Explain why unequal ownership of factors of production and unequal factor prices produce unequal incomes.
- Explain why wealth becomes more unequally distributed than income, and why the pattern persists.
- Distinguish an efficient outcome from an equitable one.
2How a free market distributes incomeHL only
In a , households own the and sell them to firms in factor markets. In return they receive factor incomes: wages for labour, rent for land, interest for capital and profit for entrepreneurship. They spend that income on goods and services in product markets. This is the two-sector .
A household's income is therefore the quantity of each factor it owns multiplied by the price that factor earns. Both are decided without any regard to what the household needs. Product markets then distribute output by ability to pay: goods and services go to those with the income to buy them, and a want that is not backed by income is not demand. The price mechanism answers the question "for whom to produce?" with "for those who can pay".
Two terms have to be kept apart. is a flow: money received over a period. is a stock: the value of the assets a household owns, less its debts, at a point in time. refers to differences in the distribution of either one.
The diagram is a circular flow model that shows why a free market results in inequality. It has no fixed layout. The version below, with two household boxes and thick and thin arrows, is one interpretation that makes the argument visible.
Check your understanding
Check your understanding
Key terms
- Circular flow of income
- A model of the flows of income, expenditure and factors of production between households, firms and other sectors, including injections and leakages.
- Factors of production
- The productive resources land, labour, capital and entrepreneurship (enterprise) used to make goods and services.
- Free-market economy
- An economic system in which resources are privately owned and the price mechanism, not the government, decides what is produced, how and for whom.
- Income
- A flow of money received over a period of time, such as wages, rent, interest, profit and transfer payments.
- Wealth
- The value of the assets a person or household owns, less its debts, at a point in time: a stock, not a flow.
- Economic inequality
- Differences in the distribution of income or wealth across households or groups.
3Why the result is unequal, and why it persistsHL only
Each of the two things that determine income, ownership and price, is unequal, and the inequality builds on itself over time.
- Unequal ownership of factors. Some households own land and capital, often inherited, and receive rent, interest and profit as well as wages. Most own only their labour. Some cannot sell labour at all: children, the elderly, and people who are ill, disabled or unemployed. In a free market with no government those households have no income.
- Unequal factor prices. A wage is set by the demand for and supply of each kind of labour. Workers whose skills are scarce and in high demand earn many times more than workers whose skills are common. Skills depend on education and training (), and wages are also affected by bargaining power and by .
- Accumulation. A high income allows saving, savings buy assets, and assets earn more income. A low income is spent entirely on consumption. Wealth is therefore distributed more unequally than income, and it is passed on through inheritance.
- Persistence across generations. A household with a low income can spend little on education and health, so its children gain fewer skills, are less productive and earn low incomes in their turn.
- Market power (topic 2.11). Where firms have , consumers pay prices above marginal cost, and the goes to the owners of the firms, who are mainly households that already own capital.
- Change and chance. New technology and trade raise the demand for some skills and lower it for others, and illness, accidents and business failure fall unevenly.
Key terms
- Human capital
- Productive knowledge, skills and capabilities embodied in people.
- Economic discrimination
- Unequal treatment of people in education, employment, credit or exchange based on characteristics unrelated to productivity or need.
4Efficient is not the same as equitableHL only
concerns the size of the total social surplus, not who receives it. A market can be allocatively efficient and still leave some households unable to afford necessities, because their wants are not backed by income and so do not count as demand. Inequality is not evidence that the market is inefficient.
means fairness, which is a normative standard: what counts as fair is a value judgement. It is not the same as , which means equal shares. To say that the market is unable to achieve equity is to judge its distribution unfair, usually on the ground that incomes reflect unequal starting points, such as inherited wealth and access to education, more than effort or choice.
Unequal rewards also do a job in a market. A higher wage for a scarce skill gives people a reason to acquire it, and profit rewards risk-taking, so some inequality is part of how the price mechanism allocates resources. The equity problem is about the degree of inequality and about households that have nothing to sell.
The market contains no mechanism that corrects its own distribution: nothing in the circular flow moves income from one group of households to another. Government policies that redistribute income and wealth are taught, and evaluated, in topic 3.4.
Check your understanding
Key terms
- Allocative efficiency
- The allocation of resources at which marginal social benefit equals marginal social cost (MB = MC when there are no externalities), so social surplus is at its maximum.
- Equity
- Fairness in the distribution of income, wealth, opportunities and economic outcomes, judged against a stated criterion.
- Equality
- A state in which everyone is treated the same or receives the same share; it is a description, whereas equity is a judgement about what is fair.
5Practice and feedback: 10 marksHL only
6Practice and feedback: 2 marksHL only
7Practice and feedback: 4 marksHL only
8Practice and feedback: 4 marksHL only
9Sources and review statusHL only
Written with AI assistance. The sources below were consulted on ; each entry says what it was used for and what it does not cover. Not reviewed by a teacher. Not approved as a finished revision resource.
Not yet checked against any source: the argument that market income depends on which factors of production a household owns (guide only); why wealth is more unequally distributed than income (saving, accumulation and inheritance); the fact itself is sourced for Great Britain; the two-box layout of the circular flow diagram, which is an interpretation of a one-line guide entry.
Sources consulted
Diploma Programme Economics guide (course first assessed 2022; October 2022 update; cover reads "First assessment 2024")
International Baccalaureate. IB curriculum document, learner's own copy, 10 Nov 2026. Printed pp. 20-21 (syllabus outline) and the topic tables on the printed pages recorded on each syllabus node; assessment outline pp. 60-65; command terms pp. 74-75. PDF page = printed page + 6.
Used for: Topic titles, the scope of each topic and SL/HL level, the assessment format and the command terms, as recorded on each syllabus node.
Limits: Read from the learner's own PDF, which is not redistributed. The IB's online copy could not be opened by automated access (HTTP 403 on 11 November 2026), so this copy was not compared with it. It sets what must be taught; it does not explain the economics. AI-assisted reading, not checked by a teacher.
OpenStax, Rice University. Reference, read in full, 11 Nov 2026. Section 1.3
Used for: Theories and models as simplified representations; the two-sector circular flow diagram (households, firms, goods-and-services market, labour market).
Limits: The diagram has no government, financial or foreign sector (the page only says they could be added) and the page does not use the terms leakages or injections. University-level US textbook: its wording, examples and diagrams are not IB wording and it is not an authority for IB scope or SL/HL level.
Principles of Microeconomics 3e: 15.4 Income Inequality: Measurement and Causes
OpenStax, Rice University. Reference, read in full, 11 Nov 2026. Section 15.4
Used for: Measuring income distribution by quintiles; constructing a Lorenz curve from cumulative quintile shares; the 45-degree line of perfect equality; causes of rising inequality (household composition, wage distribution, technology and globalisation).
Limits: Does not mention the Gini coefficient at all. Causes are those of the United States. University-level US textbook: its wording, examples and diagrams are not IB wording and it is not an authority for IB scope or SL/HL level.
Household total wealth in Great Britain: April 2018 to March 2020
UK Office for National Statistics. Real-world source, read in full, 11 Nov 2026. Statistical bulletin, main points
Used for: Wealth shares of the top 10% and bottom 50%, median household wealth, the top-1% threshold and wealth versus income Gini coefficients.
Limits: Survey data that under-records the very top; Great Britain only; pre-pandemic.
Principles of Microeconomics 3e: 3.5 Demand, Supply, and Efficiency
OpenStax, Rice University. Reference, read in full, 11 Nov 2026. Section 3.5
Used for: Definitions of consumer surplus, producer surplus and social (total) surplus; deadweight loss; the inefficiency of price floors and ceilings.
Limits: Definitions and diagrams only; no worked surplus-triangle calculations. University-level US textbook: its wording, examples and diagrams are not IB wording and it is not an authority for IB scope or SL/HL level.
Principles of Microeconomics 3e: 15.5 Government Policies to Reduce Income Inequality
OpenStax, Rice University. Reference, read in full, 11 Nov 2026. Section 15.5
Used for: Redistribution through progressive income tax and transfers; the 'ladder of opportunity' (education, training); inheritance taxes; the possible trade-off between equality and incentives, and ranges where both can rise together.
Limits: US programmes only; no universal basic income or minimum wage analysis. University-level US textbook: its wording, examples and diagrams are not IB wording and it is not an authority for IB scope or SL/HL level.